<!DOCTYPE html>
<html>
<body>
<form action="/" method="POST">
  <label for="key">Key:</label><input type="text" name="key" id="key">
  <input type="submit" value="+1">
</form>
<ul>
{% for counter in counters %}
<li>
  {{counter.key.id()|e}}: {{counter.count|e}}
</li>
{% endfor %}
</body>
</html>
